This invention relates to a high-frequency incision device, which is inserted into the patient's body through the insertion channel of an endoscope, for performing high-frequency incision of the tissue in the patient's body.
Recently, high-frequency incision devices for performing incision of the tissue in the patient's body have been proposed to replace knives and scissors. Such a high-frequency incision device has a flexible tube which is electrically insulating, and an end member having an axial through hole is secured to the distal end of the tube. A metal needle, i.e., knife, can be projected from the end of the tube through the through hole. The knife is pushed out and pulled in from the proximal end of the tube via an operating wire extending through the tube. A high frequency current is supplied to the knife through the operating wire. The knife is provided with a stopper soldered to its intermediate portion and having a diameter greater than the diameter of the through hole. The stopper restricts the extent to which the knife is projected from the end member. Excessive projection of the knife is prevented, and so is excessive cutting of the tissue of the patient's body, is thus prevented.
With the incision device of this structure, however, when the knife is heated by heat produced by the high frequency current, it is liable that the solder is melted to result in detachment of the stopper from the knife. If the stopper is detached, the knife will now project excessively from the tube end into the tissue, thus leading to excessive cutting of the tissue. In addition, there is a risk that the knife falls into the patient's body.